Add MachOObjectFile::getUuid()

[glider]

Summary

This CL introduces MachOObjectFile::getUuid(). This function returns an ArrayRef to the object file's UUID, or an empty ArrayRef if the object file doesn't contain an LC_UUID load command.
The new function is gonna be used by llvm-symbolizer.

[kledzik]

The MachOObjectFile constructor is already walking the load commands. If there is a LC_UUID, you can have the constructor save it off in an ivar.

The name findAndGetUuidCommand() is different than the other methods. Can it just be getUUID() and have it return the 16-bytes? Perhaps an ArrayRef<uint8_t> that has zero length if there is no UUID? Seems like that would be more convenient for the client.

-Nick

[glider]

Addressed Nick's comments.

[kledzik]

LGTM

[glider]

r219866, thanks!

include/llvm/Object/MachO.h

public:
   MachO::dysymtab_command getDysymtabLoadCommand() const;
   MachO::linkedit_data_command getDataInCodeLoadCommand() const;
   ArrayRef<uint8_t> getDyldInfoRebaseOpcodes() const;
   ArrayRef<uint8_t> getDyldInfoBindOpcodes() const;
   ArrayRef<uint8_t> getDyldInfoWeakBindOpcodes() const;
   ArrayRef<uint8_t> getDyldInfoLazyBindOpcodes() const;
   ArrayRef<uint8_t> getDyldInfoExportsTrie() const;
 
+  ErrorOr<MachO::uuid_command> findAndGetUuidCommand() const;
+
   StringRef getStringTableData() const;
   bool is64Bit() const;
   void ReadULEB128s(uint64_t Index, SmallVectorImpl<uint64_t> &Out) const;
 
   static StringRef guessLibraryShortName(StringRef Name, bool &isFramework,
                                          StringRef &Suffix);
 
   static Triple::ArchType getArch(uint32_t CPUType);

lib/Object/MachOObjectFile.cpp

ArrayRef<uint8_t> MachOObjectFile::getDyldInfoExportsTrie() const {
 
   MachO::dyld_info_command DyldInfo 
                    = getStruct<MachO::dyld_info_command>(this, DyldInfoLoadCmd);
   const uint8_t *Ptr = reinterpret_cast<const uint8_t*>(
                                              getPtr(this, DyldInfo.export_off));
   return ArrayRef<uint8_t>(Ptr, DyldInfo.export_size);
 }
 
+ErrorOr<MachO::uuid_command>
+MachOObjectFile::findAndGetUuidCommand() const {
+  MachOObjectFile::LoadCommandInfo Command = getFirstLoadCommandInfo();
+  uint32_t LoadCommandCount = getHeader().ncmds;
+  for (uint32_t i = 0;; ++i) {
+    if (Command.C.cmd == MachO::LC_UUID)
+      return getUuidCommand(Command);
+    if (i == LoadCommandCount - 1)
+      break;
+    else
+      Command = getNextLoadCommandInfo(Command);
+  }
+  return object_error::parse_failed;
+}
 
 StringRef MachOObjectFile::getStringTableData() const {
   MachO::symtab_command S = getSymtabLoadCommand();
   return getData().substr(S.stroff, S.strsize);
 }
 
 bool MachOObjectFile::is64Bit() const {
   return getType() == getMachOType(false, true) ||